Conventionally, in a case where a three-dimensional image is viewed by use of stereographic glasses using liquid crystal shutter lenses, right-eye images (images for a right eye) and left-eye images (images for a left eye) are alternately displayed on a display of a TV (Television) or PC (Personal Computer). While a right-eye image is being displayed, only a liquid crystal shutter provided for a right lens of the stereographic glasses is opened. In the meantime, while a left-eye image is being displayed, only a liquid crystal shutter provided for a left lens of the stereographic glasses is opened. Such operations are repeatedly performed so that a three-dimensional image is viewable through the stereographic glasses.
That is, as illustrated in FIG. 7, (i) display-refreshing timings of a display (not shown) and (ii) right-eye information and left-eye information of images to be displayed are transmitted from a wireless-signal transmitter 101 of a TV or PC. Subsequently, a wireless-signal receiving section 111 of stereographic glasses 110 receives these pieces of information, and then a liquid crystal shutter control signal timing generation section 112 receives synchronous signals and generates timings for controlling liquid crystal shutters 114 based on the synchronous signals. Then, a liquid crystal shutter control section 113 controls, based on received signals, each of the liquid crystal shutters 114 for a right lens and a left lens so that a right-eye image is observable only by a right eye and a left-eye image is observable only by a left eye, thereby allowing a viewer to see a three-dimensional image.
The following describes this process more specifically, with reference to a timing diagram shown by (a) to (d) of FIG. 8. As illustrated in (a) of FIG. 8, a synchronous signal is transmitted as a wireless signal at a display-refreshing timing of a TV or PC display. When a right-eye image is to be displayed, a “right-shutter-open” signal is transmitted as the wireless signal. When a left-eye image is to be displayed, a “left-shutter-open” signal is transmitted as the wireless signal. On the other hand, as illustrated in (b) to (d) of FIG. 8, the stereographic glasses 110 operates as follows: upon receiving the wireless signal, a left or right lens-control signal is outputted at an optimum timing in sync with a synchronous signal. More specifically, when a “right-shutter open” signal is received, a lens-control signal is outputted so as to open a corresponding one of the liquid crystal shutters 114 for the right lens. In the meantime, when a “left-shutter-open” signal is received, a lens-control signal is outputted so as to open a corresponding one of the liquid crystal shutters 114 for the left lens.
As the wireless signal, an infrared signal or an electrical-wave signal can be used.
In the aforementioned conventional technique, wireless transmission is carried out at the timing when a frame of the TV or PC display is switched to another frame. For example, when a frame frequency is 100 Hz, signals are transmitted at every 10 ms, and the stereographic glasses 110 repeatedly receive the signals at the same timings as the transmission. On this account, as the frame frequency is higher, electric-power consumption of the wireless-signal receiving section 111 tends to be larger. Further, the wireless-signal transmitter 101 is continuously connected to a power supply of the TV. However, the stereographic glasses 110 are driven by batteries. This raises such a problem that the higher the frame frequency is, the shorter the utilization life of the stereographic glasses 110 becomes.
In view of this, Patent Literature 1 discloses a wireless receiving device that is developed to avoid this problem.
In order to solve the problem, the wireless receiving device of Patent Literature 1 includes: a switch for switching between on and off of a power supply circuit of a receiving section; and switch control means. In this arrangement, even within 10 ms, the switch is turned off during an idling period in which no wireless-transmission signal is being transmitted, for example, thereby reducing electric-power consumption. More specifically, (i) a cycle of wireless-transmission signals transmitted from a transmitter side is detected, (ii) an idling period of the wireless-transmission signals is calculated based on the cycle, and (iii) the switch is turned off during the idling period.
On the other hand, there is another problem in relation to the stereographic glasses. That is, data is adversely affected by exogenous noise when the stereographic glasses receive the data, thereby causing a liquid crystal shutter control of the stereographic glasses to malfunction so that a three-dimensional image cannot be viewed normally.
In view of such a problem, a stereographic-glass device is proposed in Patent Literature 2.
In order to solve this problem, the stereographic-glass device of Patent Literature 2 is configured to close a gate so as not to receive any wireless-transmission signal during an idling period of the wireless-transmission signals even within 10 ms, for example, thereby improving noise resistance.